Numéro : 1947 - Year : 1984
Calculation of thin cavitating hydrofoils
H.LEMONNIER, Ingénieur ENSH
C.PELLONE, Docteur- Ingénieur, Attaché de Recherche au CNRS Institut de Mécanique de Grenoble
This study presents a numerical procedure to calculate a thin hydrofoil with a cavity extended from the leading edge to a point situated on the upper-side of the foil. The hypotheses used are those of a perfect, incompressible, irrotational fluid in an infinite field of flow. The problem is solved using two numerical methods based on a surface singularity distribution coupled with a minimisation procedure. They permit to evaluate the "real" pressure coefficient near the leading edge Combining this procedure with a boundary layer method, it would be possible to determine the detachment point near the leading edge. The passage between cavity and foil is characterized by an unsteady geometry ; in this study it is represented by a displacement thickness on which boundary the law of recompression is chosen.
The first method is less computer-time consuming than the second one. However, it leads to lower accuracy especially when the relative foil thickness becomes smaller than 6 % ; this withdrawal is not encountered for the second method. Comparative results of both procedures are presented for the case of subcavitating and cavitating flow.